Kant's System

Kant maintained that in all our experience, there are 2 elements to be distinguished:

1. The one due to the object (i.e. to what we have called the ‘physical object’)
2. The one due to our own nature.

The physical object is different from the associated sense-data. The sense-data are the result from an interaction between the physical object and ourselves.

So far, I agree with Kant.

But Kant is different in the way he apportions the shares of ourselves and the physical object respectively.

He thinks that:

• the crude material given in sensation—the colour, hardness, etc.—is due to the object
• we supply the arrangement in space and time and all the relations between sense-data which result from comparing one as the cause of the other

His chief reason is that we have a priori knowledge as to space, time, causality and comparison.

• But we do not have a priori knowledge of the actual crude material of sensation.

He says that anything we experience must show the characteristics affirmed of it in our a priori knowledge. This is because these characteristics are due to our own nature.

• Therefore, nothing can ever come into our experience without acquiring these characteristics.

The physical object he calls the ’thing in itself’(1).

• He regards it as essentially unknowable.

What we really know is the object that we have in our experience. This he calls the ‘phenomenon’.

• The phenomenon is a joint product of us and the thing in itself.
• It has those characteristics which are due to us.
• It therefore conforms to our a priori knowledge.
• This knowledge is true of all actual and possible experience.
  • But it does not apply outside of experience.

Thus, a priori knowledge exists. But we cannot know anything about the thing in itself.

In this way, he tries to reconcile and harmonize the contentions of the rationalists with the arguments of the empiricists.

(1) Kant’s ’thing in itself’ is identical in definition with the physical object, namely, it is the cause of sensations.

In the properties deduced from the definition it is not identical, since Kant held (in spite of some inconsistency as regards cause) that we can know that none of the categories are applicable to the ’thing in itself'.

Kant’s system has one main objection which seems fatal to any attempt to deal with the problem of a priori knowledge.

The thing to be accounted for is our certainty that the facts must always conform to logic and arithmetic.

To say that logic and arithmetic are contributed by us does not account for this.

Our nature is as much a fact of the existing world as anything. There can be no certainty that it will remain constant.

If Kant is right, then tomorrow our nature might change as to make 2 + 2 = 5.

This possibility seems never to have occurred to him. Yet it is one which utterly destroys the certainty and universality which he is anxious to vindicate for arithmetical propositions.

This possibility is inconsistent with the Kantian view that time itself is a form imposed by the subject upon phenomena, so that our real Self is not in time and has no to-morrow.

But he will still have to suppose that the time-order of phenomena is determined by characteristics of what is behind phenomena, and this suffices for the substance of our argument.

If there is any truth in our arithmetical beliefs, they must apply to things equally whether we think of them or not.

Two physical objects and two other physical objects must make four physical objects, even if physical objects cannot be experienced. To assert this is certainly within the scope of what we mean when we state that two and two are four.

Its truth is just as indubitable as the truth of the assertion that two phenomena and two other phenomena make four phenomena. Thus Kant’s solution unduly limits the scope of a priori propositions, in addition to failing in the attempt at explaining their certainty.

Apart from the special doctrines advocated by Kant, it is very common among philosophers to regard what is a priori as in some sense mental, as concerned rather with the way we must think than with any fact of the outer world. We noted in the preceding chapter the three principles commonly called ’laws of thought'.

The view which led to their being so named is a natural one, but there are strong reasons for thinking that it is erroneous. Let us take as an illustration the law of contradiction.

This is commonly stated in the form ‘Nothing can both be and not be’, which is intended to express the fact that nothing can at once have and not have a given quality.

Thus, for example, if a tree is a beech it cannot also be not a beech; if my table is rectangular it cannot also be not rectangular, and so on.

Now what makes it natural to call this principle a law of thought is that it is by thought rather than by outward observation that we persuade ourselves of its necessary truth.

When we have seen that a tree is a beech, we do not need to look again in order to ascertain whether it is also not a beech; thought alone makes us know that this is impossible.

But the conclusion that the law of contradiction is a law of thought is nevertheless erroneous. What we believe, when we believe the law of contradiction, is not that the mind is so made that it must believe the law of contradiction. This belief is a subsequent result of psychological reflection, which presupposes the belief in the law of contradiction.

The belief in the law of contradiction is a belief about things, not only about thoughts. It is not, e.g., the belief that if we think a certain tree is a beech, we cannot at the same time think that it is not a beech; it is the belief that if the tree is a beech, it cannot at the same time be not a beech.

Thus the law of contradiction is about things, and not merely about thoughts; and although belief in the law of contradiction is a thought, the law of contradiction itself is not a thought, but a fact concerning the things in the world.

If this, which we believe when we believe the law of contradiction, were not true of the things in the world, the fact that we were compelled to think it true would not save the law of contradiction from being false; and this shows that the law is not a law of thought.

A similar argument applies to any other a priori judgement. When we judge that two and two are four, we are not making a judgement about our thoughts, but about all actual or possible couples.

The fact that our minds are so constituted as to believe that two and two are four, though it is true, is emphatically not what we assert when we assert that two and two are four.

No fact about the constitution of our minds could make it true that two and two are four. Thus our a priori knowledge, if it is not erroneous, is not merely knowledge about the constitution of our minds, but is applicable to whatever the world may contain, both what is mental and what is non-mental.

The fact seems to be that all our a priori knowledge is concerned with entities which do not, properly speaking, exist, either in the mental or in the physical world. These entities are such as can be named by parts of speech which are not substantives; they are such entities as qualities and relations. Suppose, for instance, that I am in my room.

I exist. My room exists. But does ‘in’ exist?

Yet obviously the word ‘in’ has a meaning; it denotes a relation which holds between me and my room. This relation is something, although we cannot say that it exists in the same sense in which I and my room exist.

The relation ‘in’ is something which we can think about and understand, for, if we could not understand it, we could not understand the sentence ‘I am in my room’. Many philosophers, following Kant, have maintained that relations are the work of the mind, that things in themselves have no relations, but that the mind brings them together in one act of thought and thus produces the relations which it judges them to have.

This view, however, seems open to objections similar to those which we urged before against Kant. It seems plain that it is not thought which produces the truth of the proposition ‘I am in my room’.

An earwig is in my room, even if neither I nor the earwig nor any one else is aware of this truth. This truth concerns only the earwig and the room, and does not depend on anything else.

Thus relations, as we shall see more fully in the next chapter, must be placed in a world which is neither mental nor physical. This world is of great importance to philosophy, and in particular to the problems of a priori knowledge.